Cameron Diaz had a hoot on the set of Bad Teacher - because she was encouraged to swear to her heart's content.

The 38-year-old actress said it made a change from making other films, when swearing on set means reshooting.

She said: "Then you're, 'God, you can't say that. We can't use that one' [but] you're like, 'More F-bombs, give it to us' in this film. So to be able to be on set and have your director screaming that at you is a lot of fun. Everybody is just laughing."

On her role as a wayward teacher who's saving up for a breast enlargement, she said: "It wasn't a character that was originally written for a man and then made for a woman

"It was conceived as a woman. And so, it is a lot of fun. I think it is funnier. If it was a guy, it wouldn't be as funny. Guys don't need to get (breast) jobs."

The film reunites Cameron with former beau Justin Timberlake.

"We were all like, 'This is the right person for the job,'" she explained. "Any worry that we had was like what the media was going to turn it into. Because we all know what they can turn it into.

"So we were very grateful that they didn't, because there was nothing to make of it, other than two people working together, who just happened to have gone out in another time in our lives. So, it wasn't a big deal, and we had a great time. And we did the job."